Chromium iron alloy



Patented J... as, 1944 CHROMIUM IRON ALLOY Joseph J. Vetter, Hackensack, N. 1., assignor to Natural Products Refining 00., Jersey .City, N. J., a corporation of Delaware No Drawing. Application March 5, 1942, Serial No. 433,445

4 Claims.

My invention relates particularly to chromium iron alloys having many advantageous properties.

The object of my invention is to obtain an alloycontaining chromium and iron having extraordinary hardness as well as other valuable properties. Preferably, the alloys thus obtained have a high chromium content, a high carbon content and a high percentage of silicon. These alloys are capable of being used to great advantage in many different ways, but they also can be admixed with other metals or alloys to impart more or less of their properties, as desired, to the final alloys which may be thus produced. Another object is to produce the said alloys by smelting with residues obtained by the extraction of chromates from chromium iron ,ores, as for example the residue thus obtained in accordance with my patent upon Process of producing chromates, No.

of 2500 to 3000 F., but preferably 2800-F.,unti1' thoroughly liquefied; thus forming'a body of molten alloy with a supernatent layer of slag.

The smelting is carried out'in an atmosphere of the products of combustion produced. I

The alloy thus obtained will comprise from 15 i to by weight of chromium, from 1 to 3% by weight of silicon, and from 1 to 60% by weight of carbon, the balance being comprised substantially entirely of iron. The alloy containing even this high chromium content has great toughness,'

probably due to the absence of any uncombined graphitic carbon. The amount of carbon-present within the range referred to may be varied and is greater according to the increase of the amount of the above carbonaceous reducing agent put in the charge and the increase of the length of time 1,901,939, granted March'21, 1933. Further objects of my invention will appear from' the de-' tailed description of the same hereinafter.

For example, in carrying out my invention 1 may make a mixture containing a ground residue from a chromate extraction of chromium iron ores (usually containing about 50% of chromium by weight), the said residue being, forexample, V

the residue obtained in accordance with the process of my patent above referred to, although other 4 residues from chromate extraction may be used,

but the residue employed will usually contain from -4.to 8% by weight of chromium as well as oxides of iron, aluminum, silicon, calcium and magnesium.- 'The amount of said residue utilized will be about 65 to 80% by weight of the mixture to be smelted. Withthis, I admix an amount of a reducing agent, such for example as coke or soft 'coal or any other form of carbon, equal to about 10 to 15% by weight of the entire mixture to be smelted. In the mixture, Ialso introduce a sili-v cate, as aslag-forming material, such for example as a silicate-containing rock or a clay containing a silicate, for instance fire brick clay, amounting to from 5 to 15% by weight of the entire mixture. This is about enough of the silicate material to preventlthe temperature becoming so high as to melt the available refractory linings. The clay which I prefer to use for this purpose is an aluminum silicate bearing clay, or an aluminum silicate bearing rock, and I might substitutefor the coal or the slag-forming material or both in whole or in part ahigh carbon silicate-containing shale,

such as low grade high-ash coal. This mixture is the charge is in the furnace. 'When the carbon is 2% or higher, probably all of the chromium is in the form of a chromium carbide, which is extraordinarilyhard, but when the carbon is below 2% someof the chromium appears to be not in the form of a carbide so that the properties of the alloy are materially changed accordingly. The alloys thus obtained, because of their very great hardness and length of wear, have many useful applications, as for example in spiral screw conveyors for conveying gritty materials, bearings,.shafts, etc., all of which have surfaces subjected to wear and which may be, accordingly, designated bearing elements. When the alloy obtained contains from 5 to 6% by weight of carbon the'alloy is of extraordinary hardness and is 'very diilicult to, grind except with introduced intov a furnace which may be an elec- 'trically heated furnace or an electric arc furnace,

in which the mixture is heated to a temperature a diamond wheel. The alloy, having a range of carbonfrom 1 to 6%, when cast in molds of any desired. character, as for example in cast iron, graphite or sand molds, furthermore, has the properties of forged. steel, includingthe very fine grain, without having to be putthrough the expensive forging and heat-treating operations .necessary in producing forged steel. Also, the

surface of the alloy when polished is so smooth.

as to seem to have been lubricated. At high temperatures the alloy also has remarkable properties,. inasmuch as when heated up to 1500 F. or higher it has a very unusual amount of rigidity. This is demonstrated by the testing of a bar thereof supported at its ends and subjected to weights applied thereto beiwveen the supports. Under these conditions little or no sagging takes "place, whereas ordinary steel without any weights being applied will readily sag of its own weight at such temperatures. when the carbon content is r less than 5%, but at least as high as 1%, the alloy is more ductile than when the carbon is above 5% butitisstilltoohardtosawandtoohardtobe iorged. when, however, the carbon content is lowered below 1% the alloy can be sawed, drilled, etc. The alloys containing a content of 1% to 5% by weight of carbon are, therefore, useful in producing gears when great toughness is needed and brittleness is to be avoided.

When alloys are desired 01 a considerably increased toughness, as for example in making tools, hammers, chisels and cutters, I may dilute the alloy by adding from up to 90% by weight of the alloy to a mild steel (for example a steel containing about 1 by weight of carbon) in an amount to make up the balance of the 100%. Oneexample of this would be an alloy obtained by incorporating 20% by weight of any of my alloys describedinitially above, containing 1 to 6% by weight ofcarbon, with 80% by weight of the mild steel. Another example would be by incorporating 10% by weight of any of my said alloys containing from 1 to,6% by weight of carbon with 90% by weight oi the mild steel. These diluted alloys can be obtained instead, however, by adding in the original charge used in the first mentioned smelting operation herein, an equivalent amount or iron or mild steel or even an equivalent amount of iron ore and carbonaceous reducing agent for use with the iron ore. For example, hammers made with this diluted alloy have been found, by testing, to have a superior hardness and toughness than the best forged steel hammers previously available.

7 It is to be understood also that a small amount, up to a total of in any one of the above alloys, may be comprised of any one or more of the following:

Molybdenum Tungsten Manganese which may be present therein as impurities, although it is preferred not to have any of them present.

While I have described my invention above in detail I wish it to be understood that many changes may be made therein without departing from the spirit of the same.

I claim: 1

1. An alloy containing 15 to by weight of chromium, 1 to 3% byv weight of silicon, and 5 to 6% by weight of carbon, the remainder being substantially comprised oi iron.

2. An alloy containing 15 to 25% by weight of chromium, 1 to 3% by weight of silicon, and 5 to 6% by weight of carbon, the remainder being substantially comprised of iron, any other constituent present being not more than by weight of the above mentioned chromium, silicon, carbon and iron.

3. A bearing element comprising an alloy containing 15 to 25% by weight of chromium, 1 to 3% by weight of silicon, and 5 to 6% by weight of carbon, the remainder being substantially comprised of iron.

ing not more than V.% by weight of the above mentioned chromium, silicon, carbon and iron.

JOSEPH J. VEI'IER.

CERTIFICATE OF CORRECTION. Patent No. 251 258. Januar 25, 191A.

JOSEPH J. VETTER.

It is' hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 1, second column, line 8, for "l to 60% read -1 to 6%"; and that the said Letters Patent should be read with this correction therein that the same may conform tot the record of the case in the Patent Office.

Signed and sealed this 9th day of May, A. D. 191m.

Leslie Frazer 

